The present invention relates to improving the integrity and security of postage meters and in particular, microcomputerized, miniature postage meters which may be held and operated by hand, are completely portable, and may be stored in any number of small spaces such as a pocket, purse or briefcase.
Postal meters are widely used by large and small businesses. The meters in use today are, in the main, mechanical devices in which postage values are set, printed and accounted for by means of mechanical assemblies such as linkages and registers. Such meters include a mechanical ascending register which provides a record of the amount of postage printed over the life of the meter and a mechanically descending register which provides a record of the amount of postage remaining for use in the meter. To prevent the tampering of such mechanical meters, a number of different mechanical interlocks have been used. Such interlocks prevent a user from printing postage amounts without changing the contents of the ascending and descending registers. Other interlocks and seals make it nearly impossible for the user, without leaving telltale signs, to reset the descending register without having the postage meter "recharged" by the post office.
Electronic postal meters have been developed as for example the meter shown in U.S. Pat. No. 3,978,457 (Check et al). In such meters, a computer device such as a microprocessor may account for postage and cause an electronically driven printer to be set to the proper postage amount. All data, including control accounting data, is stored in electrical format memory units. A postage meter construction has been proposed in U.S. Pat. No. 4,168,533 (Schwartz), assigned to the assignee of the present invention, which describes a self-contained, microcomputerized, miniature, portable, handheld postage meter.
It has been recognized that the size and portability of these miniaturized postage meters will require increased security measures to protect the meter against improper use. Various arrangements have been developed for covering printing mechanisms which are described herein.
Covers or doors which afford protection for print heads have been designed. Examples are shown in U.S. Pat. No. 1,013,116 for Stamping Device, which includes protective cover members adapted to swing apart at a hinge when the stamp is to be used.
Other printing devices having swingable members automatically displaced in order to expose the printing indicia are shown in U.S. Pat. Nos. 3,521,555 (Price) and 3,598,948 (Hellstrom). The Price patent describes a marking device having stamp indicia carried on bands; an inking pad is swingably mounted on a shaft. The stamping apparatus in the Hellstrom patent discloses a printing type mounted on a slidable carriage for rectilinear movement within a frame toward or away from a print receiving surface. Levers support inking pad cups which are swung away from each other so that the printing type can be positioned in an opening for printing.
A portable postage meter having self-contained accounting registers is disclosed in U.S. Pat. No. 3,524,406 (Traynor). The device as illustrated has a printing assembly having a lower base and an outer housing adapted for telescopic movement with respect to the lower base. In operation, printing wheels pass through an opening in the lower base and will contact a printing surface. The amount of postage is recorded on registers. These registers are mechanically actuated through a gear train linkage. The extent of movement of the register settings is determined by the angular swing of a mechanical crank.